1. Field of the Invention
The present invention relates to an electric component, or more specifically, to an electric component that includes a function element.
2. Description of the Related Art
Electronic devices such as communication devices that utilize high-frequency bands including microwaves and millimeter waves have been used in a wide range of fields. Accordingly, electric components constituting those electronic devices have been actively manufactured. Such electric components include a micromachine switch to which a micromachine technique is applied, for example.
This electric component includes a mounting substrate, an insulating layer formed on a surface of the substrate, a signal line formed on the substrate with the insulating film interposed therebetween, a function element provided on the substrate so as to stride over the signal line, and a sealing structure formed on the substrate so as to cover the function element with a certain gap. The function element is a movable piece made of a material having a high spring characteristic such as TiN or Al, and is formed into a beam structure supported either on one end or on two ends. This function element functions as a variable electric capacitor or as a switch, which operates in response to a change in a separation distance (a gap) from the signal line.
The sealing structure is a structure configured to seal the function element inside a hollow so as to protect the function element while maintaining an operation thereof. In order to reduce manufacturing costs and to achieve downsizing, this sealing structure is formed as a thin film by a deposition method (a deposition process) (see JP-A No. 2005-207959, for example).
In this process for manufacturing the sealing structure as the thin film, a first sacrificial layer is formed on the substrate so as to form a function element on the substrate with a gap, and then the function element is formed on the first sacrificial layer. Subsequently, a second sacrificial layer is deposited on the first sacrificial layer with the function element interposed therebetween and a first sealing layer (which constitutes a part of the sealing structure) is formed on the second sacrificial layer. During or after this deposition process, multiple apertures are formed on the first sealing film so as to remove the first and second sacrificial layers. Subsequently, an etching material is introduced from the apertures to completely remove the first and second sacrificial layers. Lastly, a second sealing film (a part of the sealing structure) is formed on the first sealing film until the apertures are completely occluded. In this way, the sealing structure is formed of the first sealing film and the second sealing film.
In this manufacturing process, when the second sealing film is formed with the deposition method such as sputtering or vapor deposition, a film material (a sealing material) is deposited immediately below the aperture. For this reason, the aperture is designed to be located away from the function element so as not to deposit the film material on the function element. To obtain this structure, the sealing structure has to be formed more largely than the function element as a whole.
However, as the sealing structure is formed more largely as a whole, an internal space thereof also becomes wider. Accordingly, the volume of the sacrificial layers (the amount of the material for forming the sacrificial layers) is also increased. This requires a longer process time for removing the sacrificial layers and also increases manufacturing time of the electric component.
Moreover, when the area of the apertures is simply increased for reducing the process time for removing the sacrificial layers, process time for closing all the apertures becomes longer with the increase in the area of the apertures and the manufacturing time of the electric component therefore becomes longer.